Replace B219 Loader Control Valve

OK guys, I need some help. I'm pretty sure that the control valve on my B219 loader, on my B7100, is bad. Most of the time, I only have gravity down on the arms. If I VERY slowly and carefully press forward on the control, I can get power down, and when I can get it to work, it seems to have full power. I don't hear any squealing, so I don't think it's the pressure relief valve. Also, if I have the bucket on the ground, and tilt the bucket down, it raises the arms of the loader, but not the tractor. It's almost like the arms are in float mode, or something. Everything seems to work normally on the bucket tilt. I have taken the valve apart, but the only o-rings I see are the ones on the end, to prevent fluid from leaking. It does leak some from one of those o-rings, but I can't see how that would affect the power down function, but I could be wrong(I hope I am!). Anyway, I'd like to replace it if it can't be fixed, but I don't know the specs on it. I've read somewhere that they are power beyond type, and I would guess that they have load check, but I don't know. Is there anything else I need to know as far as specs, so I get the right valve? I don't want a joystick type. Call me old fashioned, but I really prefer the two separate handles. Or, if someone can point me to a generic replacement, that would be great.

Also, as a side question, most of the valves I see that are "ideal for loader control valves" have one port with float. From what I can find online, "float" means that the cylinder is allowed to move at will. Why would you want that on a loader?

I use float a lot on my loader. whenever I want to smooth something by back dragging I set the angle of the bucket and hit the float on the lift and backup. This allows the bucket edge to smooth the surface with just the weight of the loader arms and bucket. By changing the angle of the bucket edge you can change how aggressive the edge digs in to the surface. This is a very handy feature.
I would check the linkage between the valve and the lever. It almost sounds to me like that may be your problem rather than the valve itself.

Thanks for the quick responses!PK Fanatic: Yup, first thing I checked, fluid is full, and fresh. This is the first time I've had any of it apart, and if there was air in the system, I would have long ago worked it out. I've put over 100 hours on it since I got it. about half of it with the loader.
JDBrian: Good call on the float usage, never thought of that. The linkage works smoothly and correctly with no binding.

One thing I did think about, is that the leak is on the valve for the arm control valve, so maybe that does have something to do with it. Gonna get new O-rings today, and see.